Electrical control system



March 16, 1948. M. H. SHELDON ELECTRICAL CONTROL SYSTEM Filed Feb. 15,1946 J H 70 40W 1 01 7/166 500/?65 01 P014493 ATToRy sY Patented Mar.16, 1948 UNITED STATES PATENT OF F'ICE 7 Claims.

(Granted under the act of March 3, 1883, as amended April ,30, 1928; 3700. G. 757) This invention relates to electrical control systems and moreparticularly to control systems for lighting airplane taxiways. 'In acopendlng application submitted by the present inventor entitled Runwaylighting control, Serial Number 624,621, filed October 25, 1945, a novelcontrol system and panel for airplane runways is shown and described.The particular problems of taxiway-lighting control diiier from theproblems involved in runway-lighting control.

An object of the present invention is to provide an improved electricalcontrol system forthe lighting of airplane taxiways.

Another object is to provide a control circuit that insures correctoperation of the taxiwaylighting system.

A further object is to provide a simple and easily operable controlpanel for the taXiwayslighting system.

Further objects and advantages of thisinvention', as well as itsconstruction, arrangement and operation, will be apparent from thefollowing description and claims in connection with the 'accompanyingdrawing, in which Fig. 1 is a diagram ofthe electrical circuit of thepresent invention.

Fig. 2 is a perspectiveview of the control panel that forms part of thepresent invention.

There is shown above the dotted line It] that portion of the electricalcircuit thatis housed in the control panel I I shown in Fig.2. Thecontrol-panel circuit includes a plurality of momentary contactpushbuttons I2, one pushbutton .I2 for each taxiway on the airfield. Apilot light. I3 and nameplate I3 are associated with each pushbutton I2.A switch I4 completes the major electrical elements within the controlpanel ll and it also has its correspondingpilot light it and nameplateI3.

The electrical elements comprising the field circuit, shown below thedotted line ID, include taxiways selector relays I6 coils I5 of which,when energized, simultaneously open the normally closed relay contactsI! and close the normally opened relay contact IS, a protective relay 2l, a constant .current transformer 22, aremote-com trolled oil circuitbreaker I8 having normally .openedprimary contacts I 9 and anormally:closed control contact Zil, and a fused primary cutout 25. The primarycircuit or high-voltage circuit 1 that supplies power to the multiplebanks of lamps, which line the sides of each airfield taxiway, includesa, primary source of high-voltage power 2I, the primarycircuitbreakerl't, a constant current transformer 22, the normally iii ,corresponding pushbuttons I2.

closed relay contacts ILone for each bank of lamps (schematically shownas resistances 23) on each taxiway, a protective relay 24, and a fusedprimary cutout '25, which is normally closed.

Operation of the control panel I I is as follows.

Prior-to the selection of a taxiway, the control panel I! is notenergized and the circuit is as shown in Fig. 1 save thatfused primarycutout 25 is closed. A taxiway or combination of taxiways is selected bymomentarily pressing the V The single-pole double-throw switch I4accomplishes a dual purpose, namely,'to open or close oil circuitbreaker #8 or to erase or trip out taxiway relay selections. If thrownto relay trip position (Fig. 2) t returns to foil position, as thesingle-pole double-throw switch is spring actuated to return to its 01?position. When the pushbuttons I2 are pushed in to make momentarycontacts, the

selector relay coils I5 corresponding to the chosen pushbuttons I2 areenergized, causing relay contacts I6 to make contact with theircorresponding relay contacts 28 and also causing relay contacts.

ll to open. Th opening of contacts I7 removes the shunt acrossthe bankof lamps 23 so that the lamps light up when the primary circuit breakercontacts I9 are closed.

At this stage, the energized relays I6 are holding their correspondinglamp circuits open, the holding circuit being maintained across thenormally closed auxiliary contacts of switch 26. Once the taxiwayselection has been made, the arm 29 of the single-pole double-throwswitch I4 is made to contact the contact 21 or the one marked Closed.Thiscauses the solenoid 30 to be energized; the energized solenoid 30opens the normally closed relay contactsZU and causes normally openedrelay contacts 19 to close the primary circuit, permitting ahigh-voltage current to light the banks of lamps 23 that have been heldin readiness by the particular selector relay coils I5 that wereoriginally selected by the operator of the controlpanel I I.

If it is desired to operate a given. group of taxiways for a particularnight, the switch will be kept in contact as shown in Flg. 1 and theprimary circuit for those taxiways will be held in readiness. Y Thetaxiways are lighted by throwing the arm 29 to contactthe contact 23 andare eatinguishedby returning the arm 29 to its off position; theselected taxi-Ways are always kept in readiness unless the relay trip 26is momentarilyv opened.

The circuit shown accomplishes the following: It assures that thetaxiway relays It can be selected only when the primary circuit breakerI8 is open. If the panel operator should inadvertently close the primarycircuit, the auxiliary normally closed control relay tip or contact 20will open, shutting ofi the low voltage power source to the selectorrelay coils It, so that. no selection or, taiiiways can be made. Thecontrol scheme also assures "a correct sequence of operation. If theta'xiways selected are incorrect, the switch 26 is pressed in the relaytrip direction (Fig. 2), so erasing relays leotion, the spring 3|returning the relay 26 back to its closed position. This momentarytripping or the relay 26 "erases the selection of relays it bydeenrgizing the coils it ends new selection can now be made. Moreover,when the lighted lamps of the taXiways are extinguished, the movement ofthe arm 29 away from contact 21 assures that primary circuit currentlhigh voltage current) is always broken by the oil Circuit breakerscontacts 19, preventing any highvoltage current from breaking across theselector relay contacts 16, consequently safeguarding them from rapiddeterioration'and destruction.

The protective relay 24 shuts oli the primary high-voltage circuit incase a field conductor is broken by a crashing plane.

The present invention aiiords an extremely simple control panel foroperating a plurality of ,taxiways to be lighted singly or in groups, sosimple in fact, thata novice cannot operate it incorrectly. The controlscheme shown and described aifords a safe electricalinterlocking'between the field circuits and panel circuit and also provides afoolproof method for obtaining a correct sequence of panel operation.

No intricate electrical connections nor complicated electrical equipmentis necessary,- so that repairs, when necessary, can be -made cheaply andquickly. 7

Various modifications and changes can. be made in the above withoutdeparting from the spirit and scope of the invention as set forth in theappended claims.

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposeswithout the payment of any royalties thereon or there-for.

What is claimed is:

.1. In acontrol circuit for lighting a plurality of airfield taXiways, abank of lamps for each taxiway, a source of'high voltage current for thelamps, shunt means to direct current from each bank of lamps, circuitbreaking means for said high-voltage current, a plurality of solenoidsassociated with said shunt means, a low-voltage power source for saidsolenoids, momentary contactmeans for activating said solenoids so astore-move the shunts from said lamps, means for holdin said shunt-sremoved from the lamps,

when the momentary contact means are released, and switch means forclosing the primary circuit so that the selected lamps are lighted.

2. In a control circuit for lighting a plurality of airfield taxiways, abank of lamps for each taxiway, a primary circuit for said plurality ofbanks of lamps, switch means in said primary circuit, shunt means acrosseach bank of lamps, a secondary circuit including momentary contactmeans for removing the shunt means from preselected banks of lamps, aholding circuit whereby said preselected banks of lamps are maintainedin an open condition to receive electrical energy from the primarysource of power,

means for activating said switch means to close the primary circuit andlight the preselected banks of lamps, and electrical interlocking meanspreventing any further removal of shunt means across a bank of lampsonce the switch means closes the primary circuit, r p 0 V 3, In acontrol circuit for lighting the banks or lamps or a plurality orairfield jtaxiways, a bank of lamps for each taxiway, a primary sourceof electrical pow r for the banks of lamps, shunts across each bank oflamps, a secondary circuit including a selector relay linked toeachshunt across a bank of momentary contact means for energizingpreselected relays and cause said relays lin ed sliiints to open the so:

cuit of its associated bank of lamps, a holding circuitto maintain saidpreselected shunts in their open position, switch means for energizingand deeneigizing said preselectedbanks of lamps without deenrgiing theht lding circui 4. In a control circuit for lighting the banks of lampsof a plurality of airfield taxiways, a bank of lamps for each taxiway, aprimary source of electrical power for the banks of lamps, shunts acrosseach bank of lamps, a secondary circuit including a selector relaylinked to each shunt across a bank of lamps, momentary contact means forenergizing preselected relays an causing their linked shunts to moveaway from their associated banks of lamps, indicating means for visuallydenoting relays that have been selected, a holding circuit to maintainsaid preselected shunts in their open position, switch means forenergiain'ganddeenergizlng said preselected banks of lamps'withoutdeenergizin the holding circuit and without causing the primary circuitto break across-the selector relays.

5. In a control circuit for lighting a plurality of taxiways in whicheach taxiway is lighted by a lamp circuit from a source of power, ashunt adapted to be connected across each lamp circuit, a secondarycircuit including a selector relay linked to each shunt, contact meansfor ener gizing a preselected relay to cause its linked shunt to moveaway from its associated lamp circuit, a holding circuit to maintainsaid preselected shunt in its open position,switch means for energizingthe preselected lamp circuit Without de-energizing the holding circuitand without causing the primary circuit to break across a selectorrelay. 1 r r 6. An electrical system for energizing a selected circuitof a plurality of circuits from a source of power, said system includinga circuit having electrically operable'connecting means for energizingthe selected circuit from the source of power, switch means in the lastcircuit for operating a selected connecting means, holding meansactuated by the switch means for operating the selected connecting meansafter the switch means is inoperative, means for energizing andde-energizing the source of power, and electrical interlocking means forde-energizing the source of power during operation of the connectingmeans.

7. An electrical system for energizing at least one of a plurality ofelectrical circuits from a .primary source of power in which connectingelements are provided which are operable to energize a selected circuitfrom the primary source of power, said system comprisin a sec-. ondarycircuit having a solenoid associated with eachconnecting element,contact means for actuating selected solenoid to operate a selected 5 6connecting means to energize the selected circuit REFERENCES CITED fromthe primary Source of powerholding means The following references are ofrecord in the for actuating the selected solenoid after said contactmeans is released, means for energizing file of this patent andde-energizing the primary source of power, 5 UNITED STATES ATENTS andelectrical interlocking means for de-ener- Number N Date gizing theprimary source of power during oper- 1 9 7 337 J h st July 24' 1934ation of any solenoid. 1,972,985 Gardner Sept, 11, 1934 2,225,715Schneider Dec. 24, 1940 MALCOLM H. SHELDON. 2,351,336 Hooven June 13,1944

